The biochemistry and physiology of a newly described metabolic pathway from putrescine to 5-hydroxy-2-pyrrolidone will be studied in vivo and in vitro. Utilizing rat liver as the principle biological source, the precise enzymatic steps leading to the biosynthesis of 5-hydroxy-2-pyrrolidone will be elucidated. The metabolic fate of putrescine will be followed under conditions when ornithine decarboxylase, the first and rate limiting step in polyamine biosynthesis, is known to be significantly elevated above values obtained for appropriate matched controls. These studies will be useful in defining the physiological factors that dictate when, and the mechanism by which, putrescine is shunted to the 5-hydroxy-2-pyrrolidone pathway versus polyamine biosynthesis. Finally, to determine if 5-hydroxy-2-pyrrolidone is an intermediary metabolite or an end product of putrescine metabolism, 5-hydroxy-2-[3H] pyrrolidone will be synthesized and injected into rats. Tissues will be extracted, metabolites of 5-hydroxy-2-pyrrolidone purified and identified by gas chromatography-mass spectrometry. Putrescine and the polyamines are important metabolites in the early stages of growth and development; moreover, circulating, urinary and/or tissue polyamine levels are aberrant in several diseased states. Putrescine is also metabolized by alternate pathways; however, in contrast to polyamine biosynthesis, very little information exists regarding their tissue distribution, precise enzymatic steps, metabolic fate and physiological function(s). These studies will provide the foundation for understanding the biochemistry and physiological function of this alternate metabolic pathway. This will enhance our knowledge of fundamental biochemical and physiological processes involved in growth and development and, perhaps, shed light on the underlying cause of one or more diseases which are characterized by aberrant polyamine levels.